Nano-particles are particles having a nano-scale particle size, and exhibit a quantum confinement effect where energy required for electron transference is changed according to a size of a material, and optical, electric, and magnetic properties that are entirely different from those of a material in a bulk state due to a wide specific surface area. Accordingly, great interest has focused on availability thereof in catalyst, electric and magnetic, optical, and medical fields because of the aforementioned properties. The nano-particles may be said to be an intermediate between a bulk and a molecule, and can be synthesized in view of approaching methods in two directions, that is, a “Top-down” approaching method and a “Bottom-up” approaching method.
Examples of a method of synthesizing metal nano-particles include a method of reducing metal ions on a solution by a reducing agent, a method using a gamma ray, an electrochemical method, and the like, but in the existing methods, since it is difficult to synthesize nano-particles having a uniform size and shape or an organic solvent is used, problems such as environmental pollution and high costs occur, and thus it is difficult to perform mass production economically. Therefore, there is a demand for development of high-quality nano-particles having a uniform size.